Rosacea is a chronic dermatologic disease which typically develops in middle aged adults. Presentation varies from redness and flushing of the checks early in the disease to red, painful nodules as the disease progresses. The nodules may develop into papules and pustules. The disease progressively leads to scarring, vascularization and in some cases, swelling of the face. The effect on the nose may be especially severe, resulting in rhinophyma, a disfiguring, bluish enlargement of the nose. Rhinophyma requires surgery for correction. Once rosacea develops, it is typically present for life.
The etiology of rosacea is unknown. Some antibiotics have been used for systemic and topical treatment of rosacea. However, it is unknown whether such antibiotics treat the cause of the disease or a secondary bacterial or fungal infection at the site of lesions. It is also unknown whether the effect of antibiotics is due to a general anti-inflammatory effect. Some antibiotics (e.g. tetracycline) are ineffective when applied topically but somewhat effective when administered systemically. All known antibiotic treatments for rosacea are suppressive, rather than curative.
Rosacea treatment with topical antibiotics is long-term, usually carried out for life. The current therapy of choice is metronidazole administered topically twice daily. A 0.75% wt metronidazole medicament often used in this treatment is sold under the trademark MetroGel. However, metronidazole is only partially effective. It has an affect on papules and pustules but is generally ineffective against skin redness, telangiectases or flushing. Overall, about 50% of patients do not benefit from metronidazole treatment. The remaining patients respond initially but experience reduced effectiveness from the treatment over time. Accordingly, a need exists for more effective treatment of rosacea.